(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Monthly charts of mean, minimum, and maximum sea surface temperature of the Indian Ocean"

SPECIAL PUBLICATION 



MONTHLY CHARTS OF 

MEAN, MINIMUM, AND MAXIMUM 

SEA SURFACE TEMPERATURE 

OF THE INDIAN OCEAN 



1967 

(Reprinted 1968) 




NAVAL OCEANOGRAPHIC OFFICE 

WASHINGTON, D. C. 20390 

PRICE $2.50 



ABSTRACT 

These charts, based on ship injection temperature data, show the 
monthly maximum, minimum, and mean sea surface temperatures for 
the Indian Ocean. The data are numerous in all but the southernmost 
portion of the area, and the addition of new data probably will not greatly 
change the analysis. 

Upwelling along the coasts of the continents is evident on the charts. 
Of particular interest is a little- studied region off the coast of the Somali 
Republic, where during the southwest monsoon, the mean temperature 
in one 1° quadrangle drops to 4°F. less than the mean temperature in 
the surrounding 1° quadrangles. The maximum and minimum sea sur- 
face charts show temperature variations which are sometimes masked by 
the averaging of the temperatures on the mean charts, as in the Antarc- 
tic Convergence, which is best shown on the maximum charts. 

The graphs of monthly variability of temperature in selected locations 
show that surface temperature values in the Indian Ocean north of the 
Equator have two maximum periods during the year, as compared to one 
maximum per year in the Pacific and Atlantic Oceans. 

Because of the large quantity of data involved, these charts, in general, 
are more definitive than charts of other parameters such as salinity, except 
where the analysis were based on fewer than 25 observations per 1° quad- 
rangle or in regions where the 1° quadrangle averaging disguises more 
complex thermal structure. 



PAUL E. LA VIOLETTE 

and 

CURTIS MASON 

Physical Properties Section 

Oceanographic Analysis Division 

Marine Sciences Department 






FOREWORD 

The charts in this publication are based on ship injection 
temperature data collected over more than 100 years. They are 
being made available as an interim convenience before a more 
extensive analysis of the Indian Ocean can be made and presented 
in Publication No. 70U> "Oceanographic Atlas of the Indian Ocean, 
Section II, Physical Properties." It is hoped that this volume 
will prove useful to analysts in the interpretation of the large 
quantities of data collected during the recent International 
Indian Ocean Expedition. 



L.E. DeCAMP 

Captain, U.S. Navy 

Commander 

U.S. Naval Oceanographic Office 



III 



CONTENTS 

Page 

Foreword ii:L 

List of figures v 

Introduction 1 

Description of the charts • 

LIST OF FIGURES 



Figure 

1 

2 

3 

k 

5 

6 

7 

8 

9 
10 
11 
12 

13 
lU 
15 
16 
IT 
18 
19 
20 
21 
22 
23 
2U 

25 
26 
27 
28 

29 
30 
31 
32 
33 
3 U 
35 
36 

37 
38 
39 



Mean 
Mean 
Mean 
Mean 
Mean 
Mean 
Mean 
Mean 
Mean 
Mean 
Mean 
Mean 



sea 
sea 
sea 
sea 
sea 
sea 
sea 
sea 
sea 
sea 
sea 
sea 



surface 
surface 
surface 
surface 
surface 
surface 
surface 
surface 
surface 
surface 
surface 
surface 



temperature 
temperature 
temperature 
temperature 
temperature 
temperature 
temperature 
temperature 
temperature 
temperature 
temperature 
temperature 



(°F< 
(°F. 
(°F. 
(°F. 
(°F. 
(°F. 
(°F. 
(°F. 
(°F. 

( S' 
(°F. 

(°F. 



January h 

February. .... 5 

March 6 

April 7 

May 8 

June 9 

July 10 

August 11 

September .... 12 

October 13 

November lb 

December 15 



Minimum 
Minimum 
Minimum 
Minimum 
Minimum 
Minimum 
Minimum 
Minimum 
Minimum 
Minimum 
Minimum 
Minimum 

Maximum 
Maximum 
Maximum 
Maximum 
Maximum 
Maximum 
Maximum 
Maximum 
Maximum 
Maximum 
Maximum 
Maximum 



sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 

sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 
sea surface 



temperature (°F. 

temperature (°F. 

temperature (°F. 

temperature (°F. 

temperature (°F, 

temperature (°F. 

temperature (°F. 

temperature (°F. 

temperature (°F. 

temperature (°F. 

temperature (°F, 

temperature ( F. 

temperature (°F< 

temperature (°F. 

temperature (°F, 

temperature (°F. 

temperature (°F. 

temperature (°F. 

temperature (°F, 

temperature (°F, 

temperature (°F, 

temperature (°F. 

temperature (°F, 

temperature (°F. 



January. . . . l6 
February ... 17 

March 18 

April 19 

May 20 

June 21 

July 22 

August .... 23 
September. . . 2k 
October. ... 25 
November ... 26 
December ... 27 

January. ... 28 
February ... 29 

March 30 

April 31 

May 32 

June 33 

July 3^ 

August .... 35 
September. • • 36 
October ... 37 
November ... 38 
December ... 39 



Monthly variability of sea 
selected regions -Northwest 
Monthly variability of sea 
selected regions -Northeast 
Monthly variability of sea 
selected regions-Southwest 
Monthly variability of sea 
selected regions -Southeast 



surface temperature in 

Indian Ocean U0 

surface temperature in 

Indian Ocean h-2 

surface temperature in 

Indian Ocean hS 

surface temperature in 
Indian Ocean hi 



MONTHLY CHARTS OF MEM, MINIMUM, AND MAXIMUM 
SEA SURFACE TEMPERATURE OF THE INDIAN OCEAN 



Introduction 

The Naval Oceanographic Office is currently engaged in producing a 
series of atlases on the oceans of the world. In these atlases the 
Physical Properties Section deals mainly with the distribution and 
variation of three basic parameters: temperature, salinity, and density. 
While analyses of these parameters are made as complete as present data 
allow, undoubtedly some modifications will be necessary with the 
collection of new data. 

The charts and graphs of sea surface temperature in the atlases as 
well as in this publication, however, are based on ship injection data 
so numerous in many regions that little future modification may be 
necessary. Therefore, these charts are being published herein until a 
more extensive analysis can be presented in Pub. No. 70k "Oceanographic 
Atlas of the Indian Ocean Section II, Physical Properties." The current 
need for sea surface temperature charts for use in analyzing the inter- 
national Indian Ocean Expedition data has prompted an earlier release of 
these charts. 

Description of the charts 

Sea surface temperatures are the most easily collected of oceano- 
graphic measurements. In addition to oceanographic and naval vessels, 
ships of opportunity furnish sea surface temperature data by their 
reports of injection temperatures. 

Because injection temperatures are commonly taken below the surface 
and may be influenced by heat from the ship's engines or boilers, they 
are not individually considered as reliable as temperatures derived from 
bucket thermometers or Nansen casts. However, if taken in sufficient 
quantities by a number of ships over a prolonged period, the overall 
reliability of injection temperature data improves considerably. 

When analyzing this type of data, the following criteria are used: 
< 25 obs/l° square -- poor 
25-99 obs/l° square — good 
* 100 obs/l° square — excellent 

To show regions of reliability, those 1° squares containing 25 or 
more observations are shaded on the presented charts. 

Mean, minimum, and maximum sea surface temperatures were analyzed 
on monthly charts. These analyses were done on charts that had been 
mechanically plotted by an X-Y plotter. The data on these charts con- 
sisted of injection temperatures collected by various international 
marine organizations and are retained in punch card form at the U. S. 
National Weather Records Center, Asheville, North Carolina and at the 
Naval Oceanographic Office. The data listed in the following table for 
the marine decks cover the period from I85I+ until I96I. 

1 



Deck 


Name 


Inclusive Dates 


Number of Obs 


110 


Navy-Marine Obs. 


19^5-51 


79,444 


116 


U.S. Merchant Marine Obs. 


1949-60 


353,216 


117 


U.S. Navy Marine Obs. 


1952-61 


254,626 


318 


Japanese Marine Obs. 


1937-53 


508, 082 


119 


Japanese Marine Obs. 


1953-60 


386, 283 


184 


British Marine Obs. 


V53-6/56 


131,479 


187 


Japanese Whaling Fleet 
Obs. 


1946-56 


574 


189 


Dutch Marine Obs„ 


12/39, 9/45-6/55 


183,159 


192 


German Marine Obs. 


1859-1939 


879, 086 


193 


Netherlands Marine Obs. 


1854-1938 


2, 585, 262 


19^ 


British Marine Obs. 


1856-1953 


1,005,270 


195 


U.S. Navy Ship Logs Obs. 


1942-45 


81,177 


197 


Danish Marine Obs. 


1860-1956 


455 


281 


U.S. Navy Monthly 
Aerological Record 


1920-45 


19,236 



TOTAL 



6,467,349 



On the mean charts the machine utilized all available data, whereas 
on the minimum and maximum charts the machine was instructed to omit 
data for squares containing fewer than 10 observations. Because of the 
inherent error in injection temperature data, minimum temperature was 
taken as the first temperature class interval for which frequencies 
equal or exceed 2.5 percent of the data, while maximum temperature was 
taken as the first class interval that equals or exceeds 97.5 percent 
of the data. 

As the temperature values on the minimum and maximum charts were 
plotted for class intervals of 1°F. each, and therefore as whole numbers, 
the analysis was necessarily different from that of the mean charts, 
where the plotted values were carried to one decimal place. The method 
of analysis was intended to show the maximum intrusion of extreme 
temperatures. The minimum isoline was drawn on the warmer border of 
the temperature class interval, whereas the maximum isoline was drawn on 
the colder border of the temperature class interval, as shown in the 
following example: 



Minimum 



39 


39 39 


4o 


39 


39 39 


40 


40 


40 4o 


4o 


40 


40 40 


4o> 


40y 


^ 


\ \ 



40° 





Maximum 

40° 


39 


39 


39 


'40^ 


39 


39 


3 y. 


30- 


""40" 


Jo. 


-40' 


"4o^_ 


ko^ 


-40' 


"40" 


Jo- 


^40 


^ 


,4l' 





40° 



In addition to the horizontal charts, graphs of monthly sea surface 
temperature variation for selected locations are shown. In this presen- 
tation the percentage distribution of sea surface temperature in 1°F. 
class intervals was plotted for each month, and curves of 1, 2.5, 25, 
50, 75 > 97-5, and 99 percent were constructed. 

The choice of locations for these graphs was governed by the desire 
to demonstrate the degree of variability which occurs between various 
regions in this ocean, while attempting to select those locations with 
a sufficiently high number of observations to allow reasonable analysis. 

In comparing the analyzed charts, several features are noticeable. 
For example, the upwelling of cold water along the coasts of continents 
is evident. Of particular interest is the little- studied area off the 
east coast of the Somali Republic. During the southwest monsoon the 
persistence of the wind produces general upwelling along this coast. 
This is most evident off Ras Hafun (10°25'N., 51°l6 , E.), where the July 
mean temperature in the appropriate 1 square is nearly h°F. less than 
the July mean temperature in the surrounding 1° squares. In the graphs 
of monthly variability the double maximum-minimum characteristics of the 
Indian Ocean's north equatorial waters is strongly accentuated off Ras 
Hafun. Here, the minimum during July - August may be compared to the 
warmer minimum temperatures occurring at the same time in nearby regions. 
In addition to the temperatures shown off Ras Hafun, a low of 55 F. has 
recently been reported by the Scripps ship ARGO during the International 
Indian Ocean Expedition. 

The 1° square spacing of these charts, as well as the monthly 
treatment of data, may hide small local or temporary temperature con- 
ditions, especially on the mean charts, where the averaging of values 
may oversimplify the temperature variations of a complex region. These 
fluctuations may be better determined by referring to the maximum or 
minimum charts. For example, the Antarctic Convergence Zone, poorly 
discernible on the mean charts, is well defined on the maximum charts. 
Major current systems of the Indian Ocean, such as the North Equatorial 
Current and the Equatorial Countercurrent, are also best defined on the 
charts of maximum temperatures. In turn, currents of cool water are 
best defined on the minimum chart, as for example the intrusion of cool 
water in the South China Sea in February . 

Because of the large quantity of data involved, it is believed that 
these charts are, in general, more definitive than oceanographic charts 
of other parameters such as salinity, for which data are sparse. 
Although these charts may not be considered accurately descriptive where 
the analysis was based on fewer than 25 observations per 1 square, or in 
areas where the 1 square averaging disguises more complex thermal 
structure, they are useful tools for the ocean scientist, especially 
where other types of data do not exist or are in poor distribution. 




FIGURE 1 MEAN SEA SURFACE TEMPERATURE (°F.), JANUARY 

4 




FIGURE 2 MEAN SEA SURFACE TEMPERATURE (°F.), FEBRUARY 

5 




FIGURE 3 MEAN SEA SURFACE TEMPERATURE (°F.), MARCH 

6 




FIGURE 4 MEAN SEA SURFACE TEMPERATURE (°F.), APRIL 

7 




FIGURE 5 MEAN SEA SURFACE TEMPERATURE (°F.), MAY 

8 




FIGURE 6 MEAN SEA SURFACE TEMPERATURE (°F.), JUNE 

9 




FIGURE 7 MEAN SEA SURFACE TEMPERATURE (°F.), JULY 

10 




FIGURE 8 MEAN SEA SURFACE TEMPERATURE (°F.), AUGUST 

11 




FIGURE 9 MEAN SEA SURFACE TEMPERATURE (°F.), SEPTEMBER 

12 




FIGURE 10 MEAN SEA SURFACE TEMPERATURE (°F.), OCTOBER 

13 




FIGURE 11 MEAN SEA SURFACE TEMPERATURE (°F.), NOVEMBER 

14 




FIGURE 12 MEAN SEA SURFACE TEMPERATURE (°F.), DECEMBER 

15 




FIGURE 13 MINIMUM SEA SURFACE TEMPERATURE (°F.), JANUARY 

16 




FIGURE 14 MINIMUM SEA SURFACE TEMPERATURE (°F.), FEBRUARY 

17 




FIGURE 15 MINIMUM SEA SURFACE TEMPERATURE (°F.), MARCH 

18 




FIGURE 16 MINIMUM SEA SURFACE TEMPERATURE (°F.), APRIL 

19 




FIGURE 17 MINIMUM SEA SURFACE TEMPERATURE (°F.), MAY 

20 




FIGURE 18 MINIMUM SEA SURFACE TEMPERATURE (°F.), JUNE 

21 




FIGURE 19 MINIMUM SEA SURFACE TEMPERATURE (°F.), JULY 

22 




FIGURE 20 MINIMUM SEA SURFACE TEMPERATURE (°F.), AUGUST 

23 




FIGURE 21 MINIMUM SEA SURFACE TEMPERATURE (°F.), SEPTEMBER 

24 




FIGURE 22 MINIMUM SEA SURFACE TEMPERATURE (°F.), OCTOBER 

25 




FIGURE 23 MINIMUM SEA SURFACE TEMPERATURE (°F.), NOVEMBER 

26 




FIGURE 24 MINIMUM SEA SURFACE TEMPERATURE (°F.), DECEMBER 

27 




FIGURE 25 MAXIMUM SEA SURFACE TEMPERATURE (°F.), JANUARY 

28 




FIGURE 26 MAXIMUM SEA SURFACE TEMPERATURE (°F.), FEBRUARY 

29 




FIGURE 27 MAXIMUM SEA SURFACE TEMPERATURE (°F.), MARCH 

30 




FIGURE 28 MAXIMUM SEA SURFACE TEMPERATURE (°F.), APRIL 

31 




FIGURE 29 MAXIMUM SEA SURFACE TEMPERATURE (°F.), MAY 

32 




FIGURE 30 MAXIMUM SEA SURFACE TEMPERATURE (°F.), JUNE 

33 




FIGURE 31 MAXIMUM SEA SURFACE TEMPERATURE (°F.), JULY 

34 




FIGURE 32 MAXIMUM SEA SURFACE TEMPERATURE (°F.), AUGUST 

35 




FIGURE 33 MAXIMUM SEA SURFACE TEMPERATURE (°F.), SEPTEMBER 

36 




FIGURE 34 MAXIMUM SEA SURFACE TEMPERATURE (°F.), OCTOBER 

37 




FIGURE 35 MAXIMUM SEA SURFACE TEMPERATURE (°F.), NOVEMBER 

38 




FIGURE 36 MAXIMUM SEA SURFACE TEMPERATURE (°F.), DECEMBER 

39 




FIGURE 37 MONTHLY VARIABILITY OF SEA SURFACE TEMPERATURE IN SELECTED 
REGIONS-NORTHWEST INDIAN OCEAN 
40 




41 




FIGURE 38 MONTHLY VARIABILITY OF SEA SURFACE TEMPERATURE IN SELECTED 
REGIONS-NORTHEAST INDIAN OCEAN 

42 



(3.) 3aruvaadW3i 




I'd.) aaruvaadwdi 

I'O.) 3arUVd3dW3i 




I'd.) 3HniVa3dW31 
I'D.) 3drUVd3dW3i 







1 ! r \ \ 


'III 






§ 






| 






K 


\ \ \ 










I 


1 










o. 


J 











K 


/ / 




^_ < 


° 


/ J 


// 




z Sj 
o 8 


1 


1 ill 


_ 


8 6 


3 


1 / /// / / 




OS tt 


I 


1 / /// / 1 




5 




fill 


— 










z 


£ 


vl\ I 


- 




§ 


\\\v\ V 


- 




•MM 


1 1 1 l\l l\i\\\ \ l\l 1 1 1 1 1 1 1 1 


1 1 1 1 1 1 1 1 1 



I'd.) 3dniWd3dW31 



J J A S O N D 



REGION 4 

OF OBSERVATIONS 



- 20 68 




J J A S O 



S O N D 



11 46| 1801 152 |1 77 1162 1 18911 84 1 16711 38 1 125 



NUMBER OF OBSERVATIONS 



l_89 121 812451192 II 57 1 186|1 94 1 19612041 19611731 190 | ; 



REGION 6 

NUMBER OF OBSERVATIONS 



25712241292 |267l273|249|224l223 I 23012 



S O N D 




REGION 10 

NUMBER OF OBSERVATIONS 



72 I 88 I 78 | 69 I 77 I 54 I 92 | 66 I 60 I 64 I 46 I 



REGION 11 

NUMBER OF OBSERVATIONS 



L65 1 1 51 ll 59 |1 7912421 1791205 12001158 1 183 115711 85 



REGION 12 

NUMBER OF OBSERVATIONS 










J./0:l: 


9118711071 69 


88 |104 


i3. ; 


108111411411241 


30 




86 


s, 


^=^ 






Jfc 


u 


_ 




__ 


^-—^ 


%c 




IJc^ 


— 


— 






^^ 






0^ / -- zi 


















25 2 


e 














































f 
















S 


s 




























- 


20 




68 




1 1 1 


1 




- 



REGION 14 

OBSERVATIONS 



20 68 - 



|110|109|1191144|1041145|148|14 




S O N D 



J A S O N D 



REGION 18 

NUMBER OF OBSERVATIONS 




92 I 74 1 1 03 1 68 I 73 I 



I I I 1 I I 



NORTHEAST INDIAN OCEAN 




FIGURE 39 MONTHLY VARIABILITY OF SEA SURFACE TEMPERATURE IN SELECTED 
REGIONS-SOUTHWEST INDIAN OCEAN 

45 



Dj 3Hmva3dW31 




Do) 3»niVJi3dW31 



'J.) 3aniVH3dW3i 




z 
< 

IXJ 

u 

o 

z 
< 

z 



X 
I— 

o 

to 



46 




FIGURE 40 MONTHLY VARIABILITY OF SEA SURFACE TEMPERATURE IN SELECTED 
REGIONS-SOUTHEAST INDIAN OCEAN 
47 




O.) 3»f11Vi)3dW31 



z 
o 
o 



z 
O 
O 



z 
o 
o 



z 

o 
o 




z 
< 

UJ 

U 

o 

z 
< 

D 

z 

I- 
< 



O 
to 



(•d.) damvaddwdi 



48 



r 



~i 



hS30."1ii 






i ■ 
is 






Ubi I 111 



h 



JI j 



H 






l£Ssi||ls 



M 






g a s s a g 

St 



5 I?" a 5 • 



sill 12 






H-h 1 : 



ill ^2-oS 



lies » § §2 






m !? S^^2 

:.iis si 1 ! 



H 






| S 5 ^ « 1 1 
1 1 |f ill*". 



I -III 

* J ^ o ^ 

2k "M.3 

sill el g " 



Is 



is 



§1 



3*8 5 



s s is 

Illl 






*e§S ail 

. • e fc ^ . 2 s .. 



f-IP iill 



L 



J 



r 



n 



1 1 1 1 g 

4! | 8.1 as 



3£3g 



iiIhI J-i 



J.'J * M!°d J 



Sfs£1 



! .5 ..3 



ill 



iff 

Is* 

■S-SS 



gpi 



gjlg 



H 



|gf of i"'3 

C030.. §S£ K 



zg^yti 



1 J I o S 



>' s 2 



. s as 



iM 



f:J 



ill 



111 



Igff 

2"S g S. 



lis J S 5 !^ 



iili jfP 

Igf! 6 i|| 



H 






Sl"a> £5? • 1 g 

flf til 111? 



5 i* m £ p *§ ° 1 o* 

9|ll . I »|J3„ 






aigg$£&5B& 



L 



llbtS 



lei fill 



S5S 



I s 

f-lP fi!t 



tisi ill! 



«?!P si! | 



j 



SMITHSONIAN INSTITUTION LIBRARIES 



SMITHSONIAN INSTITUTION LIBRARIES